Mentaljudo

Wednesday, September 22, 2010

Hi there. I don't believe I'll be posting any more, seeing how this whole fiasco is wrapping up, at least the visible portions. I have been, and will continue to follow, the studies concerning microbial breakdowns of the various hydrocarbon fractions in the G.o.M., for I feel the effects will be seen more noticeably after we experience another cycle of the seasons. Take in mind when you read the articles on this blog, that there are many inaccuracies, and misunderstandings of data I read and accumulated, especially geo-data & chemistry.

In 5 months.I learned a great deal, in fact, enough to convince myself to go back to school in the spring,... a daunting task for a 38 year old high-school dropout, but one I am looking forward to, all the same.. I'm sure you have, and hopefully will to continue to seek education and clarity surrounding this event. Any questions or insults can be sent to me via email isaacnd200@gmail.com

As a parting thought, because we should really all be reminding each other to seek rational explanations for the things we see.~ Data and logic sometimes appear to be at odds with each other, but by examining causalities in public forum, we will always find the rational.

" Remember not to let yourself become jaded when all the misapplications of the science are weighed in. It is the application of the science when inappropriate or the lack of application of the science when it is appropriate that causes distress in the reasonable man."

Wednesday, September 8, 2010

*DISCLAIMER* I AM NOT A CHEMIST, I AM ONLY COMPILING INFORMATION FOR THE READER.

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Sodium bis(2-ethylhexyl) sulfosuccinate (C20H37NaO7S), often referred to as docusate sodium, Aerosol OT or AOT, is an anionic surfactant and a common ingredient in consumer products, especially laxatives of the stool softener type. AOT is the most widely used surfactant in reverse micelle encapsulation studies It is also a component of the oil dispersant Corexit.

Monday, September 6, 2010

So I continued to read up on emulsions, out of curiosity over what possibly was happening at the wellhead, originally, because there have been no previous studies confirming/disproving the effectiveness of surfactants applied to crude oil at high pressures and high temperatures. After checking into things a little more, I am doubtful of ultrasound or ultrasonic transducers being used to emulsify the oil, the equipment is not powerful enough to have any effect, but I could very well be wrong about it.

(In retrospect, I do still consider possible effects from entrained methane/H2S on the dispersed oil if there was any notable effect on the acidity of the local water during the time the oil was still flowing.)

I thought this was very odd, given the decision to apply COREXIT at the wellhead, given there is no precedence in the situation.

Here's my theory/thoughts:

I think that any chemist or engineer in the petrochemical industry ( which I am definitely not ) is well aware of cavitation and emulsions. " Hydrodynamic Cavitation Emulsion " is the term. When you emusify hydrocarbons for any reason, you add surfactants to aid in the emulsion. I honestly think that somebody realized that there was a massive opportunity to possibly to aid in emulsifying the oil at the wellhead since it was already being cavitated by the turbidity induced in the flowpath from the obstructions of the stuck drillpipe sections.

The concept is simple really, a denser fluid passes at high pressure & high temperature through an obstructed( read constricted/reduced ) flowpath, which causes the cavitation as it passes through the area back into an area of lower pressure, where it cavitates in the other fluid ( seawater ) and surfactants are added to stabilize the emulsion. The effect is greatly sped up due to the temperature difference and the ability of the ocean to act like a heatsink. The oil coming out of the wellhead is IIRC around 212-F, which drops almost immediately to the ambient temperature-37-F If you have ever seen what happens to emulsified salad dressing when you refrigerated it, you understand what I am talking about. The temperature is one of the things that actually helps keep the emulsion from breaking. You could make the same salad dressing and leave it out on the counter, it will eventually break, especially since you have not used surfactants in it......Sodium bis(2-ethylhexyl)sulfosuccinate is also a laxative, so you'd have to have one twisted sense of humor to do that to somebody,...anyway.....( that's the primary surfactant in COREXIT ). This post is put together with some fairly technical babble, just a warning. I have cited some diverse sources, so hold on to your hat.

There are typically 3 sizes of emulsions considered , with microemulsions and nanoemulsions being the smaller of the 3, they actually tend to appear clear due to the small size of the disperse phase, which also makes them very hard to see.

There are three types of emulsion instability: flocculation, creaming, and coalescence. Flocculation describes the process by which the dispersed phase comes out of suspension in flakes. Coalescence is another form of instability, which describes when small droplets combine to form progressively larger ones. Emulsions can also undergo creaming, the migration of one of the substances to the top (or the bottom, depending on the relative densities of the two phases) of the emulsion under the influence of buoyancy or centripetal force when a centrifuge is used.

Here is a great, easy to read PDF , with visuals to show what emulsion stability is and how what happens,... happens.

Surface active substances (surfactants) can increase the kinetic stability of emulsions greatly so that, once formed, the emulsion does not change significantly over years of storage.

The Bancroft Rule applies:

The Bancroft rule states: "The phase in which an emulsifier is more soluble constitutes the continuous phase."

It was named after Wilder Dwight Bancroft, an American physical chemist.

In all of the typical emulsions, there are tiny particles (discrete phase) suspended in a liquid (continuous phase). In an oil-in-water emulsion, oil is the discrete phase, while water is the continuous phase.

What the Bancroft rule states is that contrary to common sense, what makes an emulsion oil-in-water or water-in-oil is not the relative percentages of oil or water, but which phase the emulsifier is more soluble in. So even though there may be a formula that's 60% oil and 40% water, if the emulsifier chosen is more soluble in water, it will create an oil-in-water system.

There are some exceptions to Bancroft's rule, but it's a very useful rule of thumb for most systems.

The Hydrophilic-lipophilic balance (or HLB) of a surfactant can be used in order to determine whether it's a good choice for the desired emulsion or not.

In Oil in Water emulsions – use emulsifying agents that are more soluble in water than in oil (High HLB surfactants).

In Water in Oil emulsions – use emulsifying agents that are more soluble in oil than in water (Low HLB surfactants).

Bancroft's rule suggests that the type of emulsion is dictated by the emulsifier and that the emulsifier should be soluble in the continuous phase. This empirical observation can be rationalized by considering the inter-facial tension at the oil-surfactant and water-surfactant interfaces.

Surfactants have 4 classifications :anionic, cationic, non-ionic, and zwitterionic.( BTW, I was wrong about it being a Zwitt. bond.)

Sodium bis(2-ethylhexyl)sulfosuccinate ( Primary in C9500a) is anionic, from what I have learned, it's a hydrogen bond.

The length of hydrogen bonds depends on bond strength, temperature, and pressure. The bond strength itself is dependent on temperature, pressure, bond angle, and environment.They can vary in strength from very weak to extremely strong.

..Then, if you read the post I put up the other day, you see there are 3 phases of oil released underwater.

Jet Phase: The speed of the oil and natural gas being expelled from the pressurized, confined space of the well into the water makes the oil form droplets and the gas form bubbles.

Plume Phase: The momentum of these tiny droplets and bubbles drags significant volumes of sea water upward into the water column, forming a plume. In deeper water, so much water is incorporated into the plume that eventually, the oil–natural gas–water mix is no longer buoyant, and the plume will become suspended at what is called the terminal layer. If heavier components sink out of the suspension, the plume may reform and begin to rise again.

Post-terminal Phase: Once the plume reaches the final terminal layer, the rise of the oil and gas to the surface is driven purely by the buoyancy of the individual droplets and bubbles.

So that gives us: 3 sizes of emulsions, 3 types of emulsion stabilities, and 3 phases for aqueous oil dispersion.

An emulsion created by cavitation is perhaps the most effective, in terms of small particles size..

Hydrodynamic Cavitation can occur in any turbulent fluid. The turbulence produces an area of greatly reduced fluid pressure. The fluid vaporizes due to the low pressure, forming a cavity. At the edges of the cavity, small amounts of vapor break off. These form smaller cavities 100 nm to 3 mm in diameter. The smaller cavities implode under the high pressure surrounding them. This process of formation and collapse is called cavitation.

Cavitation is an enormously powerful process. Conditions in the collapsing cavity can reach 5000°C and 1000 atmospheres. The implosion takes place during the cavitation process in milliseconds, releasing tremendous energy in the form of shockwaves. The power of these waves generated by the cavitation process disrupts anything in their path.

...so that's my little bit on cavitation. On to fluid flows at high velocities.

" In some prior art Blowout Preventer (BOP) operating systems, high velocity fluid flows and low differential pressures induced vibration in the system. This vibration may result in collapse and failure of hydraulic hoses in the system. A quick dump valve has been added at or near the open port on the BOP assembly to reduce vibration and other problems. The dump valve has a vent position and an open position. Several alternative embodiments add a ball check valve assembly to the shuttle in the quick dump valve."

(fluid mechanics) Flow of a fluid over a body at speeds greater than the speed of sound in the fluid, and in which the shock waves start at the surface of the body. Also known as supercritical flow.

Mach waves

A particle moving in a compressible medium, such as air, emits acoustic disturbances in the form of spherical waves. These waves propagate at the speed of sound (M = 1). If the particle moves at a supersonic speed, the generated waves cannot propagate upstream of the particle. The spherical waves are enveloped in a circular cone called the Mach cone. The generators of the Mach cone are called Mach lines or Mach waves.

Shock waves

When a fluid at a supersonic speed approaches an airfoil (or a high-pressure region), no information is communicated ahead of the airfoil, and the flow adjusts to the downstream conditions through a shock wave. Shock waves propagate faster than Mach waves, and the flow speed changes abruptly from supersonic to less supersonic or subsonic across the wave. Similarly, other properties change discontinuously across the wave. A Mach wave is a shock wave of minimum strength. A normal shock is a plane shock normal to the direction of flow, and an oblique shock is inclined at an angle to the direction of flow. The velocity upstream of a shock wave is always supersonic. Downstream of an oblique shock, the velocity may be subsonic resulting in a strong shock, or supersonic resulting in a weak shock. The downstream velocity component normal to any shock wave is always subsonic. There is no change in the tangential velocity component across the shock.

In a two-dimensional supersonic flow around a blunt body (see illustration), a normal shock is formed directly in front of the body, and extends around the body as a curved oblique shock. At a sufficient distance away, the flow field is unaffected by the presence of the body, and no discontinuity in velocity occurs. The shock then reduces to a Mach wave.

Then I found this patent from Shell.....

Supersonic fluid separation enhanced by spray injection

The separation of liquid and/or solid components from a multiphase fluid stream passing through a supersonic fluid separator is enhanced by injecting a surface active agent ( READ: SURFACTANT )into the fluid stream passing through the separator. Preferably the spray is injected via an injection tube that has a positive or negative electrical potential, whereas one of the walls of the separator housing has an opposite electrical potential, so that the injected spray and any liquid droplets and/or particles formed around the injected nuclei are induced to flow towards said electrically loaded wall.

Shocks waves form because information about conditions downstream of a point of sonic or supersonic flow can not propagate back upstream past the sonic point.

The behavior of a fluid changes radically as it starts to move above the speed of sound (in that fluid). For example, in subsonic flow, a stream tube in an accelerating flow contracts. But in a supersonic flow, a stream tube in an accelerating flow expands. To interpret this in another way, consider steady flow in a tube that has a sudden expansion: the tube's cross section suddenly widens, so the cross-sectional area increases.

In subsonic flow, the fluid speed drops after the expansion (as expected). In supersonic flow, the fluid speed increases. This sounds like a contradiction, but it isn't: the mass flux is conserved but because supersonic flow allows the density to change, the volume flux is not constant.

So the fluid passing through the wellhead would have been restricted by the partially closed blind ram, and the trapped drillpipe sections. You could call that "choking back the flow ". The following from OnePetro:

" Wellhead chokes are installed on wells to control flow rates and to protect the reservoir and surface equipment from pressure fluctuations. Flow through the choke can be described as either critical or subcritical. In the critical-flow region, the mass flow rate reaches a maximum value that is independent of the pressure drop applied across the choke. Therefore, once critical flow is reached, any dis-turbance introduced downstream of the choke will have no effect on upstream conditions. Therefore, chokes are commonly operated under critical-flow conditions to isolate the reservoir from pressure fluctuations introduced by surface processing equipment.

A second use of wellhead chokes is to monitor production rates by operating in the subcritical-flow region, especially when oil and gas are produced from offshore or hostile environments. For these applications, it is advantageous to use MOV chokes that allow the size of the choke opening to be changed while the choke is under pressure without interruption of production. With this feature, the pressure drop across the choke, and thereby manipulation of the flow rate, can be remotely controlled. Surbey et al. I discussed in detail the application of MOV chokes in the subcritical-flow region.

This investigation presents the application of MOV chokes in the critical-flow region. The limitations of conventional correlations in predicting critical-flow behavior for MOV chokes is also discussed. A new correlation is presented to predict the transition between critical and subcritical flow that is applicable to conventional chokes as well."

To end this post :

I hope since they have finally managed to bring the BOP to the surface, that there will be some closure in this matter. We could say without a doubt, that there were certainly some effects on the phases of the oil in the water that may have had something to do with what was happening at the wellhead, ie: the COREXIT products being applied, and the restrictions in the flow.

Thursday, September 2, 2010

Why it's still a mystery how dispersants work, or where the oil is, is just plain silly. I'm still waiting for the EPA to release it's test results of the secret proprietary salts in COREXIT products, I read at the Oil Drum they have begun testing.

" The objective of dispersant use is to enhance the amount of oil that physically mixes into the water column, reducing the potential that a surface slick will contaminate shoreline habitats or come into contact with birds, marine mammals, or other organisms that exist on the water surface or shoreline. Conversely, by promoting dispersion of oil into the water column, dispersants increase the potential exposure of water-column and benthic biota to spilled oil. "

" The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such organisms are permanently attached to the bottom. "

Here's the whole article from the National academy of the Sciences.

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Approximately 3 million gallons (10,000 metric tons [tonnes]) of oil or refined petroleum product are spilled into the waters of the United States every year (NRC, 2003). This amount represents the total input from hundreds of spills, many of which necessitate timely and effective response. When these oil spills occur in the United States, the primary response methods consist of the deployment of mechanical on-water containment and recovery systems, such as booms and skimmers.

Under the Oil Pollution Act of 1990 (OPA 90), the U.S. Coast Guard (USCG) passed rules for vessel and facility response plans that specified the minimum equipment and personnel capabilities for oil containment and recovery. This requirement has significantly expanded mechanical response capability above that which existed in 1989 at the time of Tanker Vessel (T/V) Exxon Valdez spill (the event that led to passage of OPA 90). Mechanical recovery, however, is not always sufficient because conditions at the spill are often outside of the effective operating conditions of the equipment. OPA 90 also called for national and regional response teams to develop guidelines to address the use of other on-water response strategies, specifically the use of chemical dispersants and in-situ burning.

Throughout the Unites States, many regional response teams have identified zones where dispersants and in-situ burning are “pre-approved” for use. This pre-approval means that the response and re-

source agencies have determined that the Federal On-Scene Coordinator has the authority, as outlined under the pre-approval definitions, to decide to use dispersants without additional consultation. In general, these pre-approval zones are in waters beyond 3 nautical miles (nm; roughly 5 kilometers [km]) of the shoreline and in water depths greater than 30 feet (10 meters). Even with establishment of these pre-approval zones, dispersant use has been infrequent, in part reflecting the difficulty of mobilizing available equipment and dispersants within a narrow window of opportunity in which they can be effective. In areas where dispersants are not often considered, it takes more time to identify, contract, and mobilize the specialized resources needed for dispersant application.

To address the concerns regarding requisite equipment and personnel capabilities, the U.S. Coast Guard in 2002 proposed changes to the oil spill contingency planning regulations measuring the minimum capabilities for dispersant application in all pre-approved zones within acceptable time frames. With implementation of the regulations, dispersant application resources will become more readily available. The potential, therefore, for using dispersants in nearshore and shallow waters, when appropriate, will increase as well.

Oil spill dispersants do not actually reduce the total amount of oil entering the environment. Rather, they change the inherent chemical and physical properties of oil, thereby changing the oil’s transport, fate, and potential effects. Small amounts of spilled oil naturally disperse into the water column, through the action of waves and other environmental processes. The objective of dispersant use is to enhance the amount of oil that physically mixes into the water column, reducing the potential that a surface slick will contaminate shoreline habitats or come into contact with birds, marine mammals, or other organisms that exist on the water surface or shoreline. Conversely, by promoting dispersion of oil into the water column, dispersants increase the potential exposure of water-column and benthic biota to spilled oil. Dispersant application thus represents a conscious decision to increase the hydrocarbon load (resulting from a spill) on one component of the ecosystem (e.g., the water column) while reducing the load on another (e.g., coastal wetland). Decisions to use dispersants, therefore, involve trade-offs between decreasing the risk to water surface and shoreline habitats while increasing the potential risk to organisms in the water column and on the seafloor. This trade-off reflects the complex interplay of many variables, including the type of oil spilled, the volume of the spill, sea state and weather, water depth, degree of turbulence (thus mixing and dilution of the oil), and relative abundance and life stages of resident organisms.

Each spill is a unique event that unfolds over a variety of time scales. Properties of petroleum hydrocarbons immediately start to change when spilled onto water. This natural “weathering” makes the oil more difficult to disperse through time; consequently, the window of opportunity for effective dispersant application is early, usually within hours to 1–2 days after a release under most conditions, though there are exceptions. The decision to apply dispersants is thus time sensitive and complex. Given the potential impacts that dispersed oil may have on water-column and seafloor biota and habitats, thoughtful analysis is required prior to the spill event so that decisionmakers understand the potential impacts with and without dispersant application. Thus, decisionmaking regarding the use of dispersants falls into two broad temporal categories: (1) before the event during spill contingency planning; and (2) shortly after the initial event, generally within the first 12 to 48 hours.

In recognition of the increased potential to use dispersants in a variety of settings, the Minerals Management Service (MMS), the National Oceanic and Atmospheric Administration (NOAA), the USCG, and the American Petroleum Institute (API) asked the National Academies to form a committee of experts to review the adequacy of existing information and ongoing research regarding the efficacy and effects of dispersants as an oil spill response technique in the United States.2 Emphasis was placed on understanding the limitations imposed by the various methods used in these studies and on recommending steps that should be taken to better understand the efficacy of dispersant use and the effect of dispersed oil on freshwater, estuarine, and marine environments. Specifically, the committee’s task was to:

review and evaluate ongoing research and existing literature on dispersant use (including international studies) with emphasis on (a) factors controlling dispersant effectiveness (e.g., environmental conditions, dispersant application vehicles and strategies, and oil properties, particularly as the spilled oil weathers), (b) the short- and long-term fate of chemically or naturally dispersed oil, and (c) the toxicological effects of chemically and naturally dispersed oil;

evaluate the adequacy of the existing information about dispersants to support risk-based decisionmaking on response options for a variety of spatially and temporally defined oil spills;

recommend steps that should be taken to fill existing knowledge gaps, with emphasis to be placed on how laboratory and mesoscale ex-periments could inform potential controlled field trials and what experimental methods are most appropriate for such tests.

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A similar request was put to the National Academies in the mid 1980s, leading to the publication of the 1989 NRC report Using Oil Spill Dispersants on the Sea. The current report is not truly an update of the 1989 report, as it selectively revisits some topics while including discussions on issues that have emerged since that time. Many readers may, therefore, find the assessments and summaries in Using Oil Spill Dispersants on the Sea of value.

OVERARCHING CHALLENGE TO EFFECTIVE DECISION MAKING

In general, the information base used by decision makers dealing with spills in areas where the consequences of dispersant use are fairly straightforward has been adequate (for example, situations where rapid dilution has the potential to reduce the possible risk to sensitive habitat enough to allow the establishment of pre-approval zones). Many of the technical issues raised in this report, however, deal with settings where greater confidence is needed to make effective decisions regarding potential benefits or adverse impacts associated with dispersant use. In many instances where a dispersed plume may come into contact with sensitive water-column or benthic organisms and populations, the current understanding of key processes and mechanisms is inadequate to confidently support a decision to apply dispersants. Thus, such decisions regarding the potential use of dispersants in nearshore settings are creating a demand for additional information.

Research funds in the United States to support oil spill response options in general are extremely limited and declining (the total amount is less than $10 million annually). Consequently, despite the complex and numerous variables involved in risk-based decisionmaking regarding the potential use of dispersants, efforts to fill knowledge gaps must be thoroughly grounded in the recognition that no amount of research or environmental monitoring will eliminate uncertainty entirely. Failure to make a timely decision regarding dispersant application is in actuality a decision not to use dispersants, and in some instances may place some natural resources at an increased and unnecessary risk. Given the limited funding available to carry out needed research in this area, it is particularly important that research be carried out as efficiently as possible and that the research process focuses on efforts that result in sound, reproducible results that support decisionmaking. In many instances, efforts to reduce experimental complexity to ensure reproducibility or to secure cost savings have led to results that have very limited utility for making decisions in natural settings. NOAA, the Environmental Protection Agency (EPA), the Department of the Interior (including MMS and U.S. Geological Survey), USCG, relevant state agencies, industry, and appropriate international partners should work together to establish an integrated research plan which focuses on collecting and disseminating peer-reviewed information about key aspects of dispersant use in a scientifically robust, but environmentally meaningful context.

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Dr. JimClark Head of Oil Spill Research Program ... (Exxon Mobil Corporation; Head of ExxonMobil's Oil; Exxon Biomedical Sciences , Inc.) has the following to say about COREXIT products in one of his presentations, titled :

The following was a water tank test done in Alaska, concerning various COREXIT products, but strangely done in water with a very low salinity content, where sea application dispersants are almost singularly reliant on salt to maintain the H/B balance, this test was flawed, IMHO. Jim Clark specifically states that dispersants in low salt environments lose their effectiveness( stated in the above pdf )